Baking and roasting are common and popular cooking practices that require the use of an oven to perform the cooking process. For roasting meats, temperatures of 325 to 375 degrees F. are commonly used, while temperatures are often set much higher for baking, commonly to 400 to 450 degrees F. As might be expected, the oven interior including the oven racks reaches this temperature quickly and maintains these temperatures until the oven again cools down after use.
Ovens typically contain at least two wire racks used to hold bake ware and roasting pans. When the cook reaches into the oven to check on the cooking process or to remove cooked foods, it is not uncommon for him/her to accidentally brush an arm or hand against the upper rack. At the high temperatures typically used to cook/bake the food, a burn—often serious—may result.
The burn occurs almost instantly after contact with the hot metal rack, and is the result of two inherent physical properties of the metal rack: large thermal mass and high thermal conductivity. Roughly stated, thermal mass is the amount of heat contained in a given quantity of a material. Metal has a relatively high thermal mass, which means that there is a great deal of energy in the form of heat contained in the metal oven rack. Thermal conductivity is the speed at which heat transfers via conduction from one material to another. Metal has a very high thermal conductivity, making it an excellent conductor of heat. The result of this combination of a large thermal mass with a high thermal conductivity means that heat energy can be very quickly transferred from the metal oven rack to the skin, causing a burn to occur.